IEEE 802.11n spec set for first draft vote

After much wrangling between opposing interests among the members of the IEEE, a first draft for the Wi-Fi IEEE 802.11n specification will be voted on by the membership later this week.

The compromise draft, which represents the work of a joint sub-committee, is expected to pass, according to Bill McFarland, a member of the IEEE and CTO at Atheros.

Although it is now water under the bridge, the original debate divided the group between those who believed that ratification of the specification was taking too much time, represented by Enhanced Wireless Consortium (EWC) -- made up of many of the mainstream Wi-Fi players such as Atheros, Cisco, Intel, Symbol, and Toshiba -- and those that wanted more in the way of power management for handsets and VoIP devices, including Motorola, Nokia, and Samsung.

From first draft to final approval will take about a year. However, 802.11n products are expected to ship by mid-year, said McFarland.

"Long before final ratification the draft becomes stable and once the core is extremely consistent, it makes people feel comfortable to design products," said McFarland.

The benefits of 802.11n are quite dramatic, with performance at the physical layer expected to reach, in initial products, 300Mbps using two antennas, and over time scaling to 600Mbps using four antennas.

Actual throughput at the application level is expected to be 100Mbps, equivalent to 100/10Base T wired Ethernet networks.

The range of 802.11n is also expected to improve by as much as 50 percent, according to McFarland, by using Beam Forming technology that focuses energy in a particular direction on both send and receive.

Another technology called Space Time Block Coding (STBC) will reduce signal dropout by using multiple antennas for redundancy.

This technology in particular is key to enhancing the VoIP user experience.

Finally, packet aggregation and block acknowledgement protocols will reduce power consumption and data collisions in a congested environment by building a so-called super-frame to send multiple packets simultaneously.

The protocol allows designers to create a beacon that tells other devices to be quiet and tells all devices using the same access point when their timeslot is and when they can transmit. This prevents collision. It also allows devices to stay asleep saving power until it is their time to send or receive.

One of the first benefits will be for those providers looking to offer what is called in the industry "triple play service provision" -- voice, video, and data.

While it may not immediately replace wired Ethernet for the enterprise, for smaller companies using 100/10Base T, IEEE 802.11n may prove to be a less expensive alternative.